US20100107882A1 - Woven electrostatic oil precipitator element - Google Patents
Woven electrostatic oil precipitator element Download PDFInfo
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- US20100107882A1 US20100107882A1 US12/686,683 US68668310A US2010107882A1 US 20100107882 A1 US20100107882 A1 US 20100107882A1 US 68668310 A US68668310 A US 68668310A US 2010107882 A1 US2010107882 A1 US 2010107882A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/02—Plant or installations having external electricity supply
- B03C3/04—Plant or installations having external electricity supply dry type
- B03C3/09—Plant or installations having external electricity supply dry type characterised by presence of stationary flat electrodes arranged with their flat surfaces at right angles to the gas stream
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/40—Electrode constructions
- B03C3/60—Use of special materials other than liquids
- B03C3/64—Use of special materials other than liquids synthetic resins
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/66—Applications of electricity supply techniques
Definitions
- the present concept relates generally to an electrostatic precipitator for separating particles or droplets from aerosol flows, and more particularly, to an improved method and apparatus for separating oil from an oil/gas mixture.
- Electrostatic precipitation is known for removing suspended particulate matters from a gas (aerosol) flow for gas cleaning, air pollution control, oil/air separation, etc.
- the fundamental design of electrostatic precipitators has remained relatively unchanged since early applications of electrostatic precipitation in the nineteenth century.
- a high DC voltage is applied to a central electrode positioned in a grounded casing in order to cause a corona discharge to develop between the central electrode and the conductive interior surface of the casing.
- the particles are electrically charged by the corona ions.
- the charged particles are then precipitated electrostatically by the electric field onto the conductive interior surface of the casing where the charged particles neutralize.
- an electrostatic precipitator element which comprises a mesh made first, second and third insulated conductors, the first and second insulated conductors arranged relative to one another to define openings of the mesh, the third insulated conductor extending through the individual openings of the mesh, the first, second and third conductors being configured to be connected to a voltage source to thereby in use create an electric field among the first, second and third conductors; and an apparatus configured for directing an aerosol flow through the openings of the mesh, wherein, in use, particulate matters suspended in the aerosol flow are electrostatically attracted to at least one of the first. second and third conductors when said electric field is present.
- an electrostatic precipitator comprises a container including an inlet for introducing a flow of an oil/air mixture thereinto, and a first outlet for discharging an air flow and a second outlet for discharging liquid oil; and a mesh supported within the container and located between the inlet and the first outlet, the mesh being formed with at least three conductors to define openings of the mesh to permit the oil/air mixture to flow therethrough, the three conductors being individually insulated and adapted to receive an electric voltage applied thereover to create an electric field in each of the openings, thereby attracting oil particles in the oil/air mixture to an insulated surface of at least one of the three conductors to form oil droplets to be discharged through the second outlet.
- FIG. 1 is a schematic illustration of a mesh made of two insulated conductors to form an electrostatic precipitator element
- FIG. 2 is a schematic illustration of a mesh made of three insulated conductors to form an electrostatic precipitator element
- FIG. 3 is a schematic illustration in a side view of the mesh made of three insulated conductors of FIG. 2 ;
- FIG. 4 is a schematic illustration of the mesh of FIG. 1 rolled up to form a spiral shaped electrostatic precipitator element
- FIG. 5 is a perspective illustration of the spiral-shaped electrostatic precipitator element of FIG. 4 ;
- FIG. 6 is a schematic illustration in a cross-sectional view, of an electrostatic precipitator.
- FIG. 7 is a schematic illustration in a side cross-sectional view, of another electrostatic precipitator.
- a piece of mesh indicated by numeral 10 is made of, for example, two interwoven insulated electric conductors 12 and 14 , such that sections of the respective conductors 12 , 14 define openings 16 of the mesh 10 .
- the electric conductors 12 and 14 consist of a wire 18 or 20 wrapped by a layer of insulation (not indicated) such that no electric current flows between the two conductors 12 , 14 when a steady DC voltage is applied across the wires 18 , 20 of the respective conductors 12 , 14 .
- an electric field is created in each of the openings 16 of the mesh 10 when the wires 18 , 20 of the respective electric conductors 12 , 14 are connected to a source of electric voltage, for example, an AC voltage with relatively high voltage magnitude thereof, as illustrated in FIG. 1 .
- the mesh 10 with insulated electric conductors 12 , 14 connected to the source of the AC electric voltage, adapted to function as an electrostatic precipitator element, is then disposed in an environment so as to allow an aerosol flow such as an oil/air mixture (not shown) to pass through the openings 16 of the mesh 10 .
- alternating electric fields are created in the openings 16 , periodically changing the polarities of the electric fields. If the frequency of the AC voltage is expressed as 1/T, the polarity of the electric fields is reversed every T/2 seconds (or milliseconds, as the case may be).
- the particles (not shown) suspended in the aerosol flow for example the oil particles suspended in air, are electrically charged by the displacement current when the oil/air mixture flows through the openings 16 of the mesh 10 .
- the electrically charged oil particles suspended in the air flow arc attracted to one of the electric conductors 12 , 14 which has a polarity opposite to the charges of the oil particles.
- the electrically charged oil particles reach the surface of the insulation of one of the electric conductors 12 , 14 , and then are accumulated thereon due to the viscosity thereof.
- the newly electrically charged oil particles suspended in a subsequent portion of the oil/air mixture flow are attracted to the other of the electric conductors 12 , 14 which now has a polarity opposite to that of the charges of the oil particles. Therefore, the electrically charged oil particles are alternately attracted to the insulated surfaced of the respective electric conductors 12 , 14 .
- the charged oil particles of the present concept cannot be neutralized upon contact with one of the electric conductors 12 , 14 because the electric conductors 12 , 14 are insulated by the outer layer of insulation (this is a somewhat similar effect to the familiar experience of a charged birthday balloon sticking to another insulated surface, such as a wall).
- an alternating electric field created by the AC voltage not only periodically converts its polarities but also periodically changes magnitude.
- the magnitude of the voltage of the electric field increases from zero to a maximum level and then decreases to zero in the first half of the time period T and then the polarities of the electric field reverse and the magnitude of the voltage thereof also increases from zero to the maximum level and then decreases to zero in the second half of the time period T.
- oil particles in the electric field are periodically electrically charged and neutralized.
- the oil droplets will stay on the surface of the insulation of the respective electric conductors 12 , 14 by the oil's viscosity and or surface tension and thus will not be repelled by the electric conductor on which the oil particles are accumulated when that electric conductor reverses its polarity.
- the oil droplets are accumulated to a point at which the oil droplets drip from the mesh 10 under the force of gravity.
- the mesh 10 to be used as an electrostatic precipitator of the present concept functions similarly to a capacitor which forms a closed circuit in order to allow a displacement current to flow through when connected to a source of AC voltage.
- a highly dielectric insulator material for use as the insulation of the electrical conductors 12 , 14 .
- TeflonTM is preferable as the dielectric insulation of the electric conductors 12 , 14 .
- a time interval (travel t) needed for the electrically charged oil particles to travel through the alternating electric field to one of the electric conductors 12 , 14 having an instant polarity which attracts the charged oil particles is less than half the period T of the AC voltage (polarity reversal 0.5 T) needed to complete one reversal of the polarities of the AC voltage.
- the travel t is determined by a plurality of factors such as the magnitude of the AC voltage and the size of an effective space of the electric field.
- the effective space of the alternating electric field is further determined by the physical geometry, configuration and size of the openings of the mesh. Therefore, the frequency and the magnitude of the AC voltage to be applied to the electrostatic precipitator element of the present concept, is determined depending on the particular configuration of the electrostatic precipitator element.
- a source of AC voltage is preferred to be connected to the electric conductors 12 , 14 of the mesh 10
- a source of DC voltage may also be applicable for the mesh 10 used as an electrostatic precipitator element.
- the wire 18 of electric conductor 12 may be connected to a positive end of a controllable DC voltage source (not shown) and the wire 20 of the electric conductor 14 is grounded or connected to a negative end of the controllable DC voltage source.
- the controllable DC voltage is controlled to change the voltage magnitude periodically between zero and the maximum level in a predetermined frequency such that the electric field created in the respective openings 16 of the mesh 10 periodically changes strength between zero and a maximum level but does not change the polarities thereof.
- the oil particles which are suspended in the oil/air mixture and charged in the electrical field are attracted to the insulated surface of only one of the electric conductors 12 , 14 .
- an electrostatic precipitator element indicated by numeral 10 ′ is described according to another embodiment.
- the electrostatic precipitator element 10 ′ is a modification of the mesh 10 of FIG. 1 and similarly includes a mesh (not indicated) made of interwoven insulated electric conductors 12 , 14 defining a plurality of openings 16 of the mesh.
- a third insulated electric conductor 22 extends interstitially through the openings 16 of the mesh in a woven or knitted manner as shown in FIG. 3 .
- the insulated conductors 12 , 14 and 22 have wires 18 , 20 and 24 respectively.
- the respective wires 18 , 20 and 24 are connected to a source of voltage, for example a 3-phase AC voltage, in which the respective phases 1 , 2 and 3 of the AC voltage have the same frequency and magnitude but with a time differential (phase difference) relative one to another.
- a source of voltage for example a 3-phase AC voltage, in which the respective phases 1 , 2 and 3 of the AC voltage have the same frequency and magnitude but with a time differential (phase difference) relative one to another.
- electric conductors 12 , 14 can be connected to a source of AC voltage (one phase) similar to that of FIG. 1 and the electric conductor 22 is always grounded.
- the added electric conductor 22 will improve the performance of the electrostatic precipitator element 10 ′ by improving the strength distribution of the electric field in each opening 16 of the mesh 10 ′.
- the added electric conductor 22 also increases the particle attaching surface area of the electrostatic precipitator element 10 ′, which results in an improvement in precipitation efficiency.
- the openings 16 defined by the sections of the respective electric conductors 12 , 14 are sized large enough to not only allow the electric conductor 22 to extend therethrough but also to leave enough space around the electric conductor 22 to form adequate passages for an aerosol flow such as an oil/air mixture flow to pass through the electrostatic precipitator element 10 ′.
- the electrostatic precipitator 30 includes a housing or container 32 having an inlet 34 , disposed on one end of the container 32 , for introducing a flow of an oil/air mixture into the container 32 .
- the container 32 further includes an outlet, preferably a plurality of outlets 36 , disposed preferably on the other end of the container 32 spaced apart one from another along the circumference of the container 32 , for discharging an air flow, and another outlet 38 preferably disposed at a lower part of the container 32 for discharging liquid oil.
- the container 32 is preferably cylindrical for receiving a spiral roll of a mesh 10 of FIG. 1 .
- the mesh 10 of FIG. 1 is formed in a rectangular sheet having a width smaller than the length of the cylindrical container 32 , and is rolled along a length of the mesh sheet to form the spiral roll as shown in FIGS. 4 and 5 .
- the spiral roll of mesh 10 is supported within the container 32 and is located between the inlets 34 and the first outlet 36 to permit the air/oil mixture introduced from the inlets 34 , to flow therethrough.
- an inner cylindrical casing 40 is provided for supporting the spiral roll of mesh 10 and for directing the oil/air mixture flow within the container 32 .
- the inner cylindrical casing 40 has a diameter smaller than that of the container 32 and is affixed to the container 32 by for example, support elements 42 such that the cylindrical wall of the inner casing 40 is radially spaced apart from the cylindrical wall of the container 32 to form an annular passage 43 therebetween which is in communication with the outlets 36 .
- Casing 40 houses electrostatic spiral roll of mesh 10 .
- An inlet tube 46 is preferably disposed in the center of the spiral roll of mesh 10 , supported, for example by the inner casing 40 and preferably extending axially all the way through the spiral roll of mesh 10 .
- the tube 46 is in communication with or is integrated with the inlet 34 , and has a plurality of preferably holes 45 extending therethrough so as to allow air-oil flow within the tube 46 to be directed and discharged through the tube 46 into mesh 10 .
- a plurality of holes 44 are preferably defined through the cylindrical wall of the inner casing 40 and are preferably distributed over the entire area of the cylindrical wall of the inner casing 40 .
- the inner casing 40 may be used to assist directing the oil/air mixture flow into the container 32 from the mesh 10 , and to flow axially along the annular passage 43 to outlets 36 .
- a generally radial outward flow is desired because the velocity of the air-oil mixture flow will tend to reduce as it moves from the inner diameter to the outer diameter, which assists the separation effect.
- Positioning the device as shown in FIG. 6 such that the oil outlet 38 and mixture inlet 34 are both lower than the air outlet(s) 36 also allows gravity to assist the separation process.
- a source of AC voltage 48 for example, is also provided and the electric conductors 12 , 14 of the spiral roll of mesh 10 are connected to the source of the AC voltage 48 .
- the oil/air mixture flow is directed through the spiral roll of mesh 10 , oil particles suspended therein will be charged by the alternating electric field created in the vicinity of the electric conductors 12 , 14 , particularly in the individual openings 16 of the spiral roll of mesh 10 and will be attracted to the insulated surfaces of the electric conductors 12 , 14 .
- the remaining portion of the flow which is a relatively pure air flow, enters the annular passage 43 and is discharged from the outlets 36 to the atmosphere, or to a predetermined location, if desired.
- the oil particles attracted to the surfaces of the insulated electric conductors 12 , 14 are eventually accumulated to form larger oil droplets. These large oil droplets under gravity drip to a lower portion of the cylindrical wall of the container 32 and are collected as liquid oil to drain out of the container 32 through the outlet 38 .
- FIG. 7 illustrates an electrostatic precipitator 50 according to another embodiment.
- the electrostatic precipitator 50 includes a container 52 having an inlet 54 defined in one end thereof for introducing an oil/air mixture flow therein.
- the container 52 further includes a first outlet 56 on the other end thereof for discharging an air flow separated from the oil/air mixture flow entering the container 52 , and a second outlet 58 defined in a lower portion of the container 52 for discharging liquid oil separated from the oil/air mixture flow entering the container 52 .
- the container 52 is preferably in a rectangular prism configuration having substantially parallel side walls (not shown) and top and bottom walls (not indicated) to define a prismatic space for accommodating an electrostatic precipitator element 10 ′ of FIG.
- the three insulated electric conductors 12 , 14 , 22 of the electrostatic precipitator element 10 ′ are connected to a source of 3-phase AC voltage to create the desired electric fields within the container 52 such that when the oil/air mixture flow entering the container 52 through the inlet 54 passes through the plurality of layers L 1 , L 2 , . . . Ln of the electrostatic precipitator element 10 ′, the oil particles suspended in the flow are electrically charged by the electric fields and are attracted to the electrostatic precipitator element 10 ′ to form larger oil droplets thereon.
- the larger oil droplets drip onto the bottom wall of the container 52 and accumulate to form liquid oil which is directed to the second outlet 58 and drained out through the second outlet 58 .
- the remaining portion of the oil/air mixture flow which is a relatively pure air flow, is discharged through the first outlet 56 .
- a partition plate 60 within the container 52 at the end where the inlet 54 is defined.
- the partition plate 60 is spaced apart from that end wall (not indicated) of the container 52 and has a plurality of holes 62 therethrough.
- the partition plate 60 is used to redistribute the oil/air mixture flow entering the container 52 through the inlet 54 , to the entire cross-section of the container 52 , before passing through the multiple layers of the electrostatic precipitator element 10 ′ in order to improve the performance of the electrostatic precipitator element 10 ′.
- the electrostatic precipitator 50 may be positioned either in a vertical position or a horizontal position which is shown in FIG. 7 as a choice of description only. If the electrostatic precipitator 50 is in a vertical position, the outlet 58 and inlet 54 both are located in a lower end of the container 52 while the outlet 56 is located in an upper end of the container 52 .
- the electrostatic precipitator of the present concept uses woven insulated conductors such that significantly lower voltages are applied to the insulated electrodes in close proximity, in contrast to very high voltages applied to electrodes without insulation layers in conventional electrostatic precipitators, and can result in equal or higher strengths of electric fields.
- the insulated layers of the electrodes substantially eliminate the risk of arcing which may be problematic in some applications of conventional electrostatic precipitators where the fluids or gas-particle mixture may be ignited by a spark.
- This present concept permits oil/air separation in a gas turbine engine where a compact and arc-free system is preferable.
- the electrostatic precipitator element may be otherwise made of two or more insulated conductors in a preferably close relationship of any configuration (i.e. not necessarily an organized mesh) to define air passages therebetween and to create a preferably substantially continuous region of electric field having sufficient strength to achieve the separation function described herein in the vicinity of the insulated conductors.
- the electrostatic precipitator element may be configured in any desirable form, such as to increase the surface areas of the insulated surfaces of the respective conductors in order to attract the electrically charged oil particles.
- the electrostatic precipitator can also be positioned in any orientation and not just those described. Although the electrostatic precipitator is described in an application of separating oil from an oil/air mixture flow, it should be understood that the system is applicable in general for separation of suitable liquids or solid particles from gases. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure and such modifications are intended to fall within the appended claims.
Abstract
Description
- This is a Division of Applicant's U.S. patent application Ser. No. 11/669,240 filed on Jan. 31, 2007.
- The present concept relates generally to an electrostatic precipitator for separating particles or droplets from aerosol flows, and more particularly, to an improved method and apparatus for separating oil from an oil/gas mixture.
- Electrostatic precipitation is known for removing suspended particulate matters from a gas (aerosol) flow for gas cleaning, air pollution control, oil/air separation, etc. The fundamental design of electrostatic precipitators has remained relatively unchanged since early applications of electrostatic precipitation in the nineteenth century. In its simplest form for a single stage precipitator, a high DC voltage is applied to a central electrode positioned in a grounded casing in order to cause a corona discharge to develop between the central electrode and the conductive interior surface of the casing. As the gas containing suspended particles flows between the electrode and the conductive interior surface of the casing, the particles are electrically charged by the corona ions. The charged particles are then precipitated electrostatically by the electric field onto the conductive interior surface of the casing where the charged particles neutralize. This normally involves very high voltages to achieve high electric field strengths, which causes a safety issue of arcing. This may be problematic for some applications where the fluids or gas/particle mixture may be ignited by a spark, such as in a fuel system or oil system of a gas turbine engine.
- Accordingly, there is a need to provide an improved electrostatic precipitator.
- In accordance with one aspect of the present concept, there is an electrostatic precipitator element which comprises a mesh made first, second and third insulated conductors, the first and second insulated conductors arranged relative to one another to define openings of the mesh, the third insulated conductor extending through the individual openings of the mesh, the first, second and third conductors being configured to be connected to a voltage source to thereby in use create an electric field among the first, second and third conductors; and an apparatus configured for directing an aerosol flow through the openings of the mesh, wherein, in use, particulate matters suspended in the aerosol flow are electrostatically attracted to at least one of the first. second and third conductors when said electric field is present.
- In accordance with another aspect of the present concept an electrostatic precipitator comprises a container including an inlet for introducing a flow of an oil/air mixture thereinto, and a first outlet for discharging an air flow and a second outlet for discharging liquid oil; and a mesh supported within the container and located between the inlet and the first outlet, the mesh being formed with at least three conductors to define openings of the mesh to permit the oil/air mixture to flow therethrough, the three conductors being individually insulated and adapted to receive an electric voltage applied thereover to create an electric field in each of the openings, thereby attracting oil particles in the oil/air mixture to an insulated surface of at least one of the three conductors to form oil droplets to be discharged through the second outlet.
- Further details of these and other aspects of the present concept will be apparent from the detailed description and drawings included below.
- Reference is now made to the accompanying figures depicting aspects of the present concept, in which:
-
FIG. 1 is a schematic illustration of a mesh made of two insulated conductors to form an electrostatic precipitator element; -
FIG. 2 is a schematic illustration of a mesh made of three insulated conductors to form an electrostatic precipitator element; -
FIG. 3 is a schematic illustration in a side view of the mesh made of three insulated conductors ofFIG. 2 ; -
FIG. 4 is a schematic illustration of the mesh ofFIG. 1 rolled up to form a spiral shaped electrostatic precipitator element; -
FIG. 5 is a perspective illustration of the spiral-shaped electrostatic precipitator element ofFIG. 4 ; -
FIG. 6 is a schematic illustration in a cross-sectional view, of an electrostatic precipitator; and -
FIG. 7 is a schematic illustration in a side cross-sectional view, of another electrostatic precipitator. - In
FIG. 1 , a piece of mesh indicated bynumeral 10 is made of, for example, two interwoven insulatedelectric conductors respective conductors openings 16 of themesh 10. Theelectric conductors wire conductors wires respective conductors - However, an electric field is created in each of the
openings 16 of themesh 10 when thewires electric conductors FIG. 1 . Themesh 10 with insulatedelectric conductors openings 16 of themesh 10. Because of the AC voltage applied to thewires electric conductors openings 16, periodically changing the polarities of the electric fields. If the frequency of the AC voltage is expressed as 1/T, the polarity of the electric fields is reversed every T/2 seconds (or milliseconds, as the case may be). The particles (not shown) suspended in the aerosol flow, for example the oil particles suspended in air, are electrically charged by the displacement current when the oil/air mixture flows through theopenings 16 of themesh 10. The electrically charged oil particles suspended in the air flow arc attracted to one of theelectric conductors electric conductors openings 16 is reversed after the time period T, the newly electrically charged oil particles suspended in a subsequent portion of the oil/air mixture flow are attracted to the other of theelectric conductors electric conductors - In contrast to conventional electrostatic precipitators in which charged particles are neutralized on the conductive surface of an electrode having a polarity opposite to that of the charged particles, the charged oil particles of the present concept cannot be neutralized upon contact with one of the
electric conductors electric conductors electric conductors mesh 10 under the force of gravity. - The
mesh 10 to be used as an electrostatic precipitator of the present concept, functions similarly to a capacitor which forms a closed circuit in order to allow a displacement current to flow through when connected to a source of AC voltage. In order to improve the performance of the electrostatic precipitator element, it is preferable to choose a highly dielectric insulator material for use as the insulation of theelectrical conductors electric conductors - It is not recommended to use a source of AC voltage having a very high frequency such that most of the electrically charged oil particles attracted towards the
electric conductors electric conductors - Although a source of AC voltage is preferred to be connected to the
electric conductors mesh 10, a source of DC voltage may also be applicable for themesh 10 used as an electrostatic precipitator element. For example, thewire 18 ofelectric conductor 12 may be connected to a positive end of a controllable DC voltage source (not shown) and thewire 20 of theelectric conductor 14 is grounded or connected to a negative end of the controllable DC voltage source. In order to use themesh 10 as an electrostatic precipitator element of the present concept, the controllable DC voltage is controlled to change the voltage magnitude periodically between zero and the maximum level in a predetermined frequency such that the electric field created in therespective openings 16 of themesh 10 periodically changes strength between zero and a maximum level but does not change the polarities thereof. In such an application, the oil particles which are suspended in the oil/air mixture and charged in the electrical field, are attracted to the insulated surface of only one of theelectric conductors - Referring to
FIGS. 2 and 3 , an electrostatic precipitator element indicated bynumeral 10′ is described according to another embodiment. Theelectrostatic precipitator element 10′ is a modification of themesh 10 ofFIG. 1 and similarly includes a mesh (not indicated) made of interwoven insulatedelectric conductors openings 16 of the mesh. A third insulatedelectric conductor 22 extends interstitially through theopenings 16 of the mesh in a woven or knitted manner as shown inFIG. 3 . The insulatedconductors wires respective wires respective phases electric conductors FIG. 1 and theelectric conductor 22 is always grounded. The addedelectric conductor 22 will improve the performance of theelectrostatic precipitator element 10′ by improving the strength distribution of the electric field in each opening 16 of themesh 10′. The addedelectric conductor 22 also increases the particle attaching surface area of theelectrostatic precipitator element 10′, which results in an improvement in precipitation efficiency. It should be noted that theopenings 16 defined by the sections of the respectiveelectric conductors electric conductor 22 to extend therethrough but also to leave enough space around theelectric conductor 22 to form adequate passages for an aerosol flow such as an oil/air mixture flow to pass through theelectrostatic precipitator element 10′. - Referring to
FIGS. 4-6 , an electrostatic precipitator generally indicated bynumeral 30, is described according to one embodiment of the present concept. Theelectrostatic precipitator 30 includes a housing orcontainer 32 having aninlet 34, disposed on one end of thecontainer 32, for introducing a flow of an oil/air mixture into thecontainer 32. Thecontainer 32 further includes an outlet, preferably a plurality ofoutlets 36, disposed preferably on the other end of thecontainer 32 spaced apart one from another along the circumference of thecontainer 32, for discharging an air flow, and anotheroutlet 38 preferably disposed at a lower part of thecontainer 32 for discharging liquid oil. - The
container 32 is preferably cylindrical for receiving a spiral roll of amesh 10 ofFIG. 1 . Themesh 10 ofFIG. 1 is formed in a rectangular sheet having a width smaller than the length of thecylindrical container 32, and is rolled along a length of the mesh sheet to form the spiral roll as shown inFIGS. 4 and 5 . The spiral roll ofmesh 10 is supported within thecontainer 32 and is located between theinlets 34 and thefirst outlet 36 to permit the air/oil mixture introduced from theinlets 34, to flow therethrough. - Referring now to
FIG. 6 , in a preferred arrangement, an innercylindrical casing 40 is provided for supporting the spiral roll ofmesh 10 and for directing the oil/air mixture flow within thecontainer 32. The innercylindrical casing 40 has a diameter smaller than that of thecontainer 32 and is affixed to thecontainer 32 by for example,support elements 42 such that the cylindrical wall of theinner casing 40 is radially spaced apart from the cylindrical wall of thecontainer 32 to form anannular passage 43 therebetween which is in communication with theoutlets 36.Casing 40 houses electrostatic spiral roll ofmesh 10. Aninlet tube 46 is preferably disposed in the center of the spiral roll ofmesh 10, supported, for example by theinner casing 40 and preferably extending axially all the way through the spiral roll ofmesh 10. Thetube 46 is in communication with or is integrated with theinlet 34, and has a plurality of preferably holes 45 extending therethrough so as to allow air-oil flow within thetube 46 to be directed and discharged through thetube 46 intomesh 10. Similarly to theinlet tune 46, a plurality ofholes 44 are preferably defined through the cylindrical wall of theinner casing 40 and are preferably distributed over the entire area of the cylindrical wall of theinner casing 40. Theinner casing 40 may be used to assist directing the oil/air mixture flow into thecontainer 32 from themesh 10, and to flow axially along theannular passage 43 tooutlets 36. A generally radial outward flow is desired because the velocity of the air-oil mixture flow will tend to reduce as it moves from the inner diameter to the outer diameter, which assists the separation effect. The lower the velocity of the air near the exit, the lower the aerodynamic forces will be on the oil causing oil to exit with the air (undesired). Positioning the device as shown inFIG. 6 , such that theoil outlet 38 andmixture inlet 34 are both lower than the air outlet(s) 36 also allows gravity to assist the separation process. - A source of
AC voltage 48, for example, is also provided and theelectric conductors mesh 10 are connected to the source of theAC voltage 48. When the oil/air mixture flow is directed through the spiral roll ofmesh 10, oil particles suspended therein will be charged by the alternating electric field created in the vicinity of theelectric conductors individual openings 16 of the spiral roll ofmesh 10 and will be attracted to the insulated surfaces of theelectric conductors annular passage 43 and is discharged from theoutlets 36 to the atmosphere, or to a predetermined location, if desired. The oil particles attracted to the surfaces of the insulatedelectric conductors container 32 and are collected as liquid oil to drain out of thecontainer 32 through theoutlet 38. -
FIG. 7 illustrates anelectrostatic precipitator 50 according to another embodiment. Theelectrostatic precipitator 50 includes acontainer 52 having aninlet 54 defined in one end thereof for introducing an oil/air mixture flow therein. Thecontainer 52 further includes afirst outlet 56 on the other end thereof for discharging an air flow separated from the oil/air mixture flow entering thecontainer 52, and asecond outlet 58 defined in a lower portion of thecontainer 52 for discharging liquid oil separated from the oil/air mixture flow entering thecontainer 52. Thecontainer 52 is preferably in a rectangular prism configuration having substantially parallel side walls (not shown) and top and bottom walls (not indicated) to define a prismatic space for accommodating anelectrostatic precipitator element 10′ ofFIG. 2 , which is multi-folded to form a plurality of layers L1, L2, . . . Ln. The three insulatedelectric conductors electrostatic precipitator element 10′ (seeFIG. 2 ) are connected to a source of 3-phase AC voltage to create the desired electric fields within thecontainer 52 such that when the oil/air mixture flow entering thecontainer 52 through theinlet 54 passes through the plurality of layers L1, L2, . . . Ln of theelectrostatic precipitator element 10′, the oil particles suspended in the flow are electrically charged by the electric fields and are attracted to theelectrostatic precipitator element 10′ to form larger oil droplets thereon. Under force of gravity, the larger oil droplets drip onto the bottom wall of thecontainer 52 and accumulate to form liquid oil which is directed to thesecond outlet 58 and drained out through thesecond outlet 58. The remaining portion of the oil/air mixture flow which is a relatively pure air flow, is discharged through thefirst outlet 56. - It is preferable to position a
partition plate 60 within thecontainer 52 at the end where theinlet 54 is defined. Thepartition plate 60 is spaced apart from that end wall (not indicated) of thecontainer 52 and has a plurality ofholes 62 therethrough. Thepartition plate 60 is used to redistribute the oil/air mixture flow entering thecontainer 52 through theinlet 54, to the entire cross-section of thecontainer 52, before passing through the multiple layers of theelectrostatic precipitator element 10′ in order to improve the performance of theelectrostatic precipitator element 10′. - The
electrostatic precipitator 50 may be positioned either in a vertical position or a horizontal position which is shown inFIG. 7 as a choice of description only. If theelectrostatic precipitator 50 is in a vertical position, theoutlet 58 andinlet 54 both are located in a lower end of thecontainer 52 while theoutlet 56 is located in an upper end of thecontainer 52. - The electrostatic precipitator of the present concept uses woven insulated conductors such that significantly lower voltages are applied to the insulated electrodes in close proximity, in contrast to very high voltages applied to electrodes without insulation layers in conventional electrostatic precipitators, and can result in equal or higher strengths of electric fields. In addition, the insulated layers of the electrodes substantially eliminate the risk of arcing which may be problematic in some applications of conventional electrostatic precipitators where the fluids or gas-particle mixture may be ignited by a spark.
- This present concept permits oil/air separation in a gas turbine engine where a compact and arc-free system is preferable.
- The above description is meant to be exemplary only and one skilled in the art will recognize that changes may be made to the embodiments described without departure from the scope of the concept disclosed. For example, alternative to a mesh woven by insulated conductors, the electrostatic precipitator element may be otherwise made of two or more insulated conductors in a preferably close relationship of any configuration (i.e. not necessarily an organized mesh) to define air passages therebetween and to create a preferably substantially continuous region of electric field having sufficient strength to achieve the separation function described herein in the vicinity of the insulated conductors. Furthermore, the electrostatic precipitator element may be configured in any desirable form, such as to increase the surface areas of the insulated surfaces of the respective conductors in order to attract the electrically charged oil particles. The electrostatic precipitator can also be positioned in any orientation and not just those described. Although the electrostatic precipitator is described in an application of separating oil from an oil/air mixture flow, it should be understood that the system is applicable in general for separation of suitable liquids or solid particles from gases. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure and such modifications are intended to fall within the appended claims.
Claims (8)
Priority Applications (1)
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US12/686,683 US7862650B2 (en) | 2007-01-31 | 2010-01-13 | Woven electrostatic oil precipitator element |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US11/669,240 US20080178737A1 (en) | 2007-01-31 | 2007-01-31 | Woven electrostatic oil precipitator element |
US12/686,683 US7862650B2 (en) | 2007-01-31 | 2010-01-13 | Woven electrostatic oil precipitator element |
Related Parent Applications (1)
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US11/669,240 Division US20080178737A1 (en) | 2007-01-31 | 2007-01-31 | Woven electrostatic oil precipitator element |
Publications (2)
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US20100107882A1 true US20100107882A1 (en) | 2010-05-06 |
US7862650B2 US7862650B2 (en) | 2011-01-04 |
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US11/669,240 Abandoned US20080178737A1 (en) | 2007-01-31 | 2007-01-31 | Woven electrostatic oil precipitator element |
US12/686,683 Active US7862650B2 (en) | 2007-01-31 | 2010-01-13 | Woven electrostatic oil precipitator element |
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US11/669,240 Abandoned US20080178737A1 (en) | 2007-01-31 | 2007-01-31 | Woven electrostatic oil precipitator element |
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CA (1) | CA2619154C (en) |
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US20110232492A1 (en) * | 2007-08-03 | 2011-09-29 | Daihatsu Motor Co., Ltd. | Electrode for plasma generation |
WO2023018415A1 (en) * | 2021-08-12 | 2023-02-16 | Johnson Medtech Llc | Flexible plate structure for smoke-reduction in surgical procedures |
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US20080178737A1 (en) * | 2007-01-31 | 2008-07-31 | Pratt & Whitney Canada Corp. | Woven electrostatic oil precipitator element |
US20130098767A1 (en) * | 2011-10-24 | 2013-04-25 | General Electric Company | Oil degradation byproducts removal system |
US8935910B2 (en) | 2011-10-24 | 2015-01-20 | General Electric Company | Rotary oil degradation byproducts removal system |
JP6104950B2 (en) * | 2013-02-07 | 2017-03-29 | 三菱日立パワーシステムズ環境ソリューション株式会社 | Dust collector, dust collector electrode selection method and dust collector method |
US10016766B2 (en) * | 2016-03-24 | 2018-07-10 | The Boeing Company | Dust mitigation system utilizing conductive fibers |
CN106076625B (en) * | 2016-08-11 | 2017-06-16 | 天津大学 | A kind of micro- electrostatic filter of cylindrical shape |
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US8623125B2 (en) * | 2007-08-03 | 2014-01-07 | Daihatsu Motor Co., Ltd. | Electrode for plasma generation |
WO2023018415A1 (en) * | 2021-08-12 | 2023-02-16 | Johnson Medtech Llc | Flexible plate structure for smoke-reduction in surgical procedures |
Also Published As
Publication number | Publication date |
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CA2619154A1 (en) | 2008-07-31 |
US7862650B2 (en) | 2011-01-04 |
US20080178737A1 (en) | 2008-07-31 |
CA2619154C (en) | 2014-09-16 |
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